The present invention relates to radio-frequency identification (RFID) tags. The invention also relates to RFID apparatus and methodology that enable the RFID tags to operate with multiple read ranges and/or that enable tags to have their operating characteristics modified.
Automatic identification is the broad term applying to a host of technologies that are used to help machines identify objects. Automatic identification is often coupled with automatic data capture. Therefore, companies wanting to identify items are able to capture information about the items, to store the captured information in a computer, and to retrieve selectively the information from the computer for a variety of useful purposes, all with minimal human labor.
One type of automatic identification technology is radio-frequency identification (RFID). Radio-frequency identification is a generic term for technologies that use radio waves to automatically identify objects. There are several conventional methods of identifying objects using RFID, the most common of which is to store a serial number (and other information, if desired) that identifies a product on a microchip that is attached to an antenna. The chip and the antenna together define an RFID transponder circuit. The antenna enables a remote reader that has a transceiver to communicate with the chip, and enables the chip to transmit identification information back to the reader when actuated to do so by the reader. The reader converts the radio waves returned from the RFID tag into a form that can then be utilized by a computer.
RFID tags are often produced in rolls or sheets of tags, in which the tags are spaced closely together. In certain applications it is desirable to read each of the tags prior to further processing, for example, to check the operability of the tags. Because the tags are closely spaced, there is a certain degree of cross coupling between the tags which diminishes the effectiveness of the reading operation. In other applications, it is desirable to read a tag from a direction that is orthogonal to the normal propagation direction of the tag. However, the antenna of the circuit may not be configured to effectively receive energy from such orthogonal directions.
In view of the foregoing, there is a need in the art for an RFID tag with a simple, inexpensive mechanism by which certain parameters of the tag, for example, its read range and/or its orthogonal readability, can be selectively altered between two desired states.